Self-opening die head



April 29, 1930. A. F. BREITENSTEIN SELF| OPENING DIE HEAD Filed July 18, 1929 2 Sheets-Sheet l m 5 W 5 m April 29, 1930. A. F. BREITENSTElN SELF OYPENING ms HEAD Filed July 18, 1929 2 Sheets-Sheet 2 ,J MrM Patented Apr. 29, 1930 UNITED STATES PATENT OFFICE ALBERT Ill. BBEITENSTEIN, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO THE GEO- METRIC TOOL COMPANY, OF NEW HAVEN, CONNEC ICUT, A CORPORATION SELF-OPENING DIE HEAI Application filed July 18,

This invention relates. to an improvement in self-opening die-heads and particularly to that class of self-opening die-heads having their chasers mounted in overhanging chasercarriers which project forward from the front end of the die-head structure so as to permit the use of the so-called long-life chasers.

The object of my present invention is to provide a reliable, convenient and accurate o die-head of the forwardly-projecting overhanging chaser-carrier type just above re- Ierred to which will produce threads correctboth in form and lead.

With this object in view my invention consists in a self-opening die-head characterized as above and having certain details of construction and combinations of parts as will be hereinafter described and particularly recited in the claim.

Heretofore several styles of self-opening die-heads of the type above referred to have been desi ned but they all have possessed two major defects discussed in the two succeeding paragraphs as compared to the class of selfopening die-heads in which the chasers themselves are mounted directly in the body-member of the die-head.

The canting of the chaser-carriers laterally in the plane of the cutting-face of the chasers-a defect now common-results in distortion in the form of the thread being out and errors in its lead, due to the altered helical angle of the chaser-teeth and their failure to track properly.

The other major defect-only slightly less objectionable than the firstis the canting of the chaser-carriers in a direction perpendicular to the cutting-face of the chasers', so that tapered threads are produced when that effect is not desired.

As a result of prolonged study and experimentation, I have evolved the particular details of supporting the chaser-carriers for radial movement set forth herein and have succeeded in reducing the former objections to this type of die-head to a negligible minimum.

In the accompanying drawings:

Fi 1 is a view in side elevation of a self- 50 opening die-head embodying my invention,

1929. Serial ifo. 379,164.

the operating-sleeve being partly broken Fig. 2 is ajliew thereof in front elevation;

Fig. 3 is a view thereof in broken longitudinal section, taken on the line 3-3 of Fig. 2 and omitting the upper chaser-carrier and chaser;

Fig. 4 is a broken detail view in longitudinal section on the line 4-4 of Fig. 2;

Fig. 5 is a view in front elevation of one of the chaser-carriers shown with a chaser installed therein;

Fig. 6 is a side view thereof looking in the direction of the arrow 6 in Fig. 5;

Fig. 7 is a similar view but looking in the direction of arrow 7 in Fig. 5; and

Fig. 8 is a view corresponding to Fig. 4, but showing a key interposed between the forwardly-facing anchoring-shoulder of the chaser-carrier tang and'the rearwardly-facing anchoring-shoulder of the body-member.

in carrying out my invention as shown in Figs. 1 to 7 inclusive, I employ a plurality (four-more or less) of chaser-carriers corresponding to each other, so that a description of one, together with its co-acting parts, will serve for all. Each chaser-carrier comprises a body-portion 10 having offsetting from it at one end an integral rearwardlyprojecting tang 11. The rear face of the body-portion 10 is carefully ground to form a rearwardly-facing bearing-surface 12 which is adapted to ride upon the front face 13 of the'body-member 14 of a die-head structure, which may be of any approved construction.

While I have shown the rear faces 12 of the body-portions 10 of the chaser-carriers as bearing upon the front face of a one-piece body-member 14, it is obvious, without illustration, that the said body-member may be composed of a multiple number of parts, without departing from my invention as defined in the claim.

The tang 11 of the chaser-carrier is adapted to ride in one of a plurality of radial guide grooves 15 formed in the body-member 14 so as to open through its front face and intersect both its periphery and its internal bore 16. The said tang is formed in the side face, opposite to the Ody-portion 10, with a radial groove 17, the rear wall of which wardly-facing anchoring-shoulder co-acting with the forwardly-facing anchorin -shoulder 18 of the tang 11 so as to effective y resist .outward draft upon the chaser-carrier in the direction of the arrow A (Fig. 3).

The body-member of each of the chasercarriers is formed with an inwardly-opening dovetail-groove 21 for the reception of a dovetail rib 22 formed upon the outer face of a bar-like die or chaser 23 formed upon its inner face with cutting-teeth 24 in the usual manner of thread-cutting chasers. For the purpose of adjustably clamping the chaser 23 in the chaser-carrier, I form the body-portion 10 thereof with a slot 25 extending parallel with the front face of the same and intersecting at one of its ends the dovetail-groove 21 and at its opposite end a tubular bore 26 extending from side to side of the chaser-carrier near and parallel with the front face thereof, so as to form a thin wall 27 which will readily flex.

The formation of the slot 25 and the bore 26 virtually converts the front end of the body-portion 10 of the chaser-carrier into a resilient clamping-finger 28 which will flex at the point 27 to clamp the dovetail-rib 22 of the chaser under the urge of two clampingscrews 29 passing through the clampingfinger 28 into which they are countersunk and into the main portion of the body-memher, as clearly shown in Fig. 4 of the drawings.

To provide for the radial adjustment of the chaser 23, I provide the body-member of the chaser-carrier with an adjustingscrew 30 extending parallel with the dovetailrib 22 of the chaser and impinging against one end thereof, as shown in Fig. 7.

The outer end of the tang-portion of each of the chaser-carriers is formed with an inclined cam-surface 31 adapted to co-act with a similarly-inclined internal cam-surface 32, one of which is formed at four (more or less) equidistant points within the forward end of an operating-sleeve 33 which is adapted to slide axially upon the periphery of the body-member 14, so as to act when slid forward, to move the chaser-carriers inward into their cutting positions and to maintain them in such position, and when slid rearward in any approved manner to permit the said chaser-carriers to move outward into their retired positions under the urge of hollow spring-pressed retracting-plungers 34, one of which is provided for each chasercarrier.

by the retracting-pl nger 34, as clearly shown in Fig. 3 ofthe drawings.

Tht retracting-plunger 34 is urged outward so as to exert outward force upon its complementary chaser-carrier by a helical spring 38 having its inner end impinging on the bottom of the bore 35 and its outer end impinging against the outer end of an inwardlyopening axial socket 39 formed in the plunger 34. A forwardly-extending pin 40, mount-- ed in the body-member 14 and projecting into the bore 35, serves to limit the outward movement of the said plunger.

Instead of employing a rib 19 for the purpose of providing a rearwardly-facing anchoring-shoulder 20, I may provide the same, as shown in Fig. 8, by cutting a radial groove 41 in the side wall of the guideroove 15. In the construction shown in this gure, a radial key 42 is interposed between the rearwardlyfacing shoulder 20 and the forwardly-facing shoulder 18.

During the cutting operation, the strains developed tend to rock the chasers'23 in the direction of the arrows B and C which, in turn, exert an outward draft upon the tang 11 of the chaser-carrier in the direction of the arrow A and tend to rock the chaser-carrier and to force the bearing-surface 13 thereof into engagement with the front face of the body-member 14 in the direction of the arrow D.

By means of the particular construction employed in which the tang 11- of the chasercarrier is formed with a forwardly-facing substantially-radial anchoring-shoulder for co-action directly or indirectly with the rearwardly-facing shoulder 21 provided in the side wall of the guide-groove 15, and in which the rear face of the chaser-carrier bears for reciprocating movement upon the front face of the body-member of the die-head, the strains above described'are effectively resisted, so as to prevent the canting of the chasers in the plane of the cutting-faces thereof, so that threads may be out which are accurate, both as to form and lead.

The anchoring-means described further effectively acts to resist the strains perpendicular to the cutting-face of the chasers, so that the same are prevented from assuming a socalled bell-mouth position and cutting taper-threads when that form of thread is not desired.

I claim:

In a self-opening die-head, the combination pendlcular canting of with a body-member having an axial bore and formed in its outer end wlth a plurality of substantially-radial guide-grooves opemng through its front of a rearwardly-facing anchoring-shoulder rovided in a side-wall of each of the sai guidegrooves; a plurality of chaser-carriers odily movable radially in the said body-member and each comprising a body-portion bearin at its rear face upon the front face of the sai body-member and formed with an integral rearwardly-projecting tang reciprocating in one of the said guide-grooves; and a forwardly-facing anchoring-shoulder formed in one side of the said tang and located in position to co-act with the anchoring-shoulder of the said uide-groove to resist the lateral and perthe chaser-carrier in conjunction with the bearing of the rear face of the body-portion of the same upon the front face of the body-member.

In testimony whereof, I have signed this specification. I

ALBERT F. BREITENSTEIN.

face and through its penphcry and intersecting the said bore; 

